The Applicant has proposed an improved flow meter in U.S. Pat. No. 7,980,127 as shown in FIGS. 1, 2 and 3, which includes a transparent holder 10 with a frame edge 11 formed at one side. The frame edge 11 has a first screw hole 12 at one end communicating with the interior of the flow meter 1 and screwing with a regulation valve 13. The regulation valve 13 has an external thread portion 131 at one end to screw with the first screw hole 12, a fastening screw hole 132 inside the same end, and an adjustment knob 133 at another end. The first screw hole 12 is connected to a first fastening portion 122 via a first connection rib 121. The frame edge 11 also has a second screw hole 14 at another end communicating with the interior of the flow meter 1. The second screw hole 14 is connected to two second fastening portions 142 respectively via a second connection rib 141. After the flow meter 1 has been coupled with the regulation valve 13 via the regulation valve 13 screwing with the first screw hole 12, they are handed over to the factories. In the factory, the operator couples the regulation valve 13 with a pipe through the fastening screw hole 132, but the flow meter 1 thus formed has deficiency to be mended, notably:
The transparent holder 10 is made of acrylic. As the second screw hole 14 is connected to two second fastening portions 142 via two second connection ribs 141, and the first screw hole 12 is only connected to one first fastening portion 122 via one first connection rib 121, two sides of the second screw hole 14 are stronger in structure than that of the first screw hole 12. When the operator fastens the pipe to the fastening screw hole 132 of the regulation valve 13 (i.e. the flow meter 1) by excessive turning forces, the outer side around the first screw hole 12 is easily to be damaged to generate a fracture 101 (referring to FIG. 3). This could impact the fastening structure of the regulation valve 13 in the transparent holder 10. As a result, the lifespan of the flow meter 1 is reduced and an extra cost incurs to the manufacturer.